American Idol has lost viewers this season, but the drop is smaller than it was in Season 11.

Over the first four nights of Season 12, the Fox singing competition is down 16% in viewers year-to-year (16.6 million vs. 19.7 million). However, that decline is smaller than the 21% year-to-year drop over the first four nights of last season.

The gap is much wider when it comes to advertiser-coveted young adults (18-to-49). Over four nights, Idol is down 12% compared to Season 11, which was down a comparable 27% from Season 10.

Audience declines are expected as a show ages.

Idol, which has added Mariah Carey, Nicki Minaj and Keith Urban to its judging panel, attracted 15.5 million viewers to its Baton Rouge, La., audition show on Thursday, which amounts to just a 5% drop from the previous Thursday.

That follows Wednesday's auditions from Charlotte, N.C., which featured Minaj storming off the set. That show drew 16.1 million viewers, a 10% decline from the Season 12 premiere a week earlier.

Idol was the most-watched program on Wednesday and Thursday.

Glee, which followed Idol on Thursday, scored its biggest audience (6.9 million) since September.